The growth of the electroless plating industry, especially its application in the automotive sector has led to increased quantities of hypophosphites being consumed. This led to rapid increases in production of the hypophosphites and also to increase in the amount of by-products resulting from this expansion.
A method of manufacturing hypophosphites is through the reaction of caustic and phosphorus followed by a lime precipitation of the crude calcium phosphite by-product. The precipitate is removed from the reactor and is currently discarded by burial in a secure landfill. This precipitate is removed from the reactor in a semi-solid mass and is commonly referred to as "hypo mud".
In the manufacture of sodium hypophosphite, sodium hydroxide is used as a caustic, and reacted with phosphorus, followed by a lime treatment. Dependent upon the purity of the chemicals used, the desired product and the precipitate could contain many types of impurities. The precipitate that was previously discarded contained quantites of lime, calcium phosphite, alumina, sand, to mention but a few. From an industrial standpoint, the reclamation of such a type of waste did not encourage processing but rather discarding. With the advent of environmental rules and regulations concerning waste disposal the disposal of such mud by landfill burial is an environmental problem, that the chemical industry must solve. An approach taken was the investigation of this mud to determine if the offensive substances could be removed and if usable chemicals or by-products could be obtained. One of these approaches is the basis for this invention.
Although many of the materials contained in this "hypo mud" are essential to our environment and play an important part in the life cycle on earth, the presence of specific species and quantities thereof must be controlled. The disposal through landfill burial is although a suitable and acceptable procedure, if the material to be buried meets a fixed environmentally safe criteria. In this application, the disposal of "hypo mud", there should be removal of the phosphorus components as well as other metallic components. Although this invention does not claim to provide a completely safe and secure material for landfill burial, it is at least a step in the direction of providing a material that can be easily, efficiently and economically disposed of without danger to the environment.
It is an object of this invention to provide an environmentally secure waste product that can be easily and universally discarded.
An object of this invention is to reclaim useful chemical materials from the "hypo mud".
An object of this invention is to obtain phosphorous acid as a by-product of the "hypo mud".